Changed the way how CPU activity is monitored: instead of taking the active

time of the idle thread as a measure, we now compute the CPU activity on
each thread switch - the time the CPU worked is the total of user and kernel
time a thread spent during its quantum.
Unlike before, this mechanism works correctly on SMP machines. I hope this
works as expected :)


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@16193 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/cpu.h

@@ -23,6 +23,12 @@ typedef union cpu_ent {
 		// thread.c: used to force a reschedule at quantum expiration time
 		int preempted;
 		timer quantum_timer;
+
+		// keeping track of CPU activity
+		bigtime_t active_time;
+		bigtime_t last_kernel_time;
+		bigtime_t last_user_time;
+
 		bool disabled;
 	} info;
 } cpu_ent __attribute__((aligned(64)));
@@ -39,6 +45,7 @@ status_t cpu_preboot_init(struct kernel_args *args);
 status_t cpu_init(struct kernel_args *args);
 status_t cpu_init_post_vm(struct kernel_args *args);
 status_t cpu_init_post_modules(struct kernel_args *args);
+bigtime_t cpu_get_active_time(int32 cpu);
 
 cpu_ent *get_cpu_struct(void);
 extern inline cpu_ent *get_cpu_struct(void) { return &gCPU[smp_get_current_cpu()]; }

headers/private/kernel/thread.h

@@ -34,7 +34,6 @@ status_t thread_per_cpu_init(int32 cpuNum);
 void thread_yield(void);
 void thread_exit(void);
 
-bigtime_t thread_get_active_cpu_time(int32 cpuNum);
 int32 thread_max_threads(void);
 int32 thread_used_threads(void);
 
@@ -47,8 +46,14 @@ static thread_id thread_get_current_thread_id(void);
 static inline thread_id
 thread_get_current_thread_id(void)
 {
-	struct thread *t = thread_get_current_thread();
+	struct thread *thread = thread_get_current_thread();
-	return t ? t->id : 0;
+	return thread ? thread->id : 0;
+}
+
+static inline bool
+thread_is_idle_thread(struct thread *thread)
+{
+	return thread->entry == NULL;
 }
 
 thread_id allocate_thread_id(void);

src/system/kernel/Jamfile

@@ -25,7 +25,7 @@ KernelMergeObject kernel_core.o :
 	module.c
 	port.c
 	real_time_clock.c
-	scheduler.c
+	scheduler.cpp
 	sem.c
 	shutdown.c
 	signal.c

src/system/kernel/cpu.c

@@ -8,9 +8,9 @@
 
 /* This file contains the cpu functions (init, etc). */
 
-#include <kernel.h>
+
 #include <cpu.h>
-#include <vm.h>
+#include <thread_types.h>
 #include <arch/cpu.h>
 #include <boot/kernel_args.h>
 
@@ -58,6 +58,30 @@ cpu_preboot_init(kernel_args *args)
 }
 
 
+bigtime_t
+cpu_get_active_time(int32 cpu)
+{
+	bigtime_t activeTime;
+	cpu_status state;
+
+	if (cpu < 0 || cpu > smp_get_num_cpus())
+		return 0;
+
+	// We need to grab the thread lock here, because the thread activity
+	// time is not maintained atomically (because there is no need to)
+
+	state = disable_interrupts();
+	GRAB_THREAD_LOCK();
+
+	activeTime = gCPU[cpu].info.active_time;
+
+	RELEASE_THREAD_LOCK();
+	restore_interrupts(state);
+
+	return activeTime;
+}
+
+
 void
 clear_caches(void *address, size_t length, uint32 flags)
 {

src/system/kernel/scheduler.cpp

@@ -127,11 +127,6 @@ scheduler_remove_from_run_queue(struct thread *thread)
 static void
 context_switch(struct thread *fromThread, struct thread *toThread)
 {
-	// track kernel time (user time is tracked in thread_at_kernel_entry())
-	bigtime_t now = system_time();
-	fromThread->kernel_time += now - fromThread->last_time;
-	toThread->last_time = now;
-
 	toThread->cpu = fromThread->cpu;
 	fromThread->cpu = NULL;
 
@@ -223,6 +218,23 @@ scheduler_reschedule(void)
 	nextThread->state = B_THREAD_RUNNING;
 	nextThread->next_state = B_THREAD_READY;
 
+	// track kernel time (user time is tracked in thread_at_kernel_entry())
+	bigtime_t now = system_time();
+	oldThread->kernel_time += now - oldThread->last_time;
+	nextThread->last_time = now;
+
+	// track CPU activity
+	if (!thread_is_idle_thread(oldThread)) {
+		oldThread->cpu->info.active_time +=
+			(oldThread->kernel_time - oldThread->cpu->info.last_kernel_time)
+			+ (oldThread->user_time - oldThread->cpu->info.last_user_time);
+	}
+
+	if (!thread_is_idle_thread(nextThread)) {
+		oldThread->cpu->info.last_kernel_time = nextThread->kernel_time;
+		oldThread->cpu->info.last_user_time = nextThread->user_time;
+	}
+
 	if (nextThread != oldThread || oldThread->cpu->info.preempted) {
 		bigtime_t quantum = 3000;	// ToDo: calculate quantum!
 		timer *quantumTimer = &oldThread->cpu->info.quantum_timer;

src/system/kernel/system_info.c

@@ -10,7 +10,7 @@
 #include <system_info.h>
 #include <arch/system_info.h>
 
-#include <vm.h>
+#include <cpu.h>
 #include <debug.h>
 #include <port.h>
 #include <real_time_clock.h>
@@ -18,6 +18,7 @@
 #include <smp.h>
 #include <team.h>
 #include <thread.h>
+#include <vm.h>
 #include <vm_page.h>
 
 #include <string.h>
@@ -41,7 +42,7 @@ _get_system_info(system_info *info, size_t size)
 	info->cpu_count = smp_get_num_cpus();
 
 	for (i = 0; i < info->cpu_count; i++)
-		info->cpu_infos[i].active_time = thread_get_active_cpu_time(i);
+		info->cpu_infos[i].active_time = cpu_get_active_time(i);
 
 	// ToDo: Add page_faults
 	info->max_pages = vm_page_num_pages();

src/system/kernel/thread.c

@@ -1281,34 +1281,6 @@ spawn_kernel_thread_etc(thread_func function, const char *name, int32 priority,
 }
 
 
-bigtime_t
-thread_get_active_cpu_time(int32 cpuNum)
-{
-	bigtime_t activeTime;
-	cpu_status state;
-
-	if (cpuNum < 0 || cpuNum > B_MAX_CPU_COUNT || sIdleThreads[cpuNum] == NULL)
-		return 0;
-
-	activeTime = system_time();
-
-	// we need to grab the thread lock here, because the thread activity
-	// time is not maintained atomically (because there is no need to)
-
-	state = disable_interrupts();
-	GRAB_THREAD_LOCK();
-
-	// TODO: this is wrong - the idle threads are arbitrarly executed by the CPUs
-	//		there is no CPU affinity!
-	activeTime -= sIdleThreads[cpuNum]->kernel_time;
-
-	RELEASE_THREAD_LOCK();
-	restore_interrupts(state);
-
-	return activeTime;
-}
-
-
 int32
 thread_max_threads(void)
 {
@@ -1371,6 +1343,7 @@ thread_init(kernel_args *args)
 		thread->next_state = B_THREAD_READY;
 		sprintf(name, "idle thread %lu kstack", i + 1);
 		thread->kernel_stack_area = find_area(name);
+		thread->entry = NULL;
 
 		if (get_area_info(thread->kernel_stack_area, &info) != B_OK)
 			panic("error finding idle kstack area\n");